The Elastic Emission Machining (EEM) is a finishing process for the surface of ceramic parts. In the EEM, the ceramic part is submerged into a liquid interface that contains abrasive particles, and then a spindle rotates a spheric tool rapidly, forcing the abrasive particles into contact with the ceramic part surface. Due to the fact that it is a finishing process, the part that goes through EEM have a high aggregated value from previous machining process. Thus, with monitoring of this process, failures that would cause the parts to be discarded can be detected. One of the most preeminent non-intrusive methods of machining processes monitoring is the digital processing of in-situ acquired acoustic emission (AE) signals. In recent published papers, a low-cost piezoelectric transducer has shown great results as an alternative to traditional AE sensors when applied in monitoring of other machining processes such as grinding and dressing. Among the methods of evaluating sensor’s response, the Pencil Lead Break (PLB) method has shown to be effective when applied to ceramic parts. The presents work aims to evaluate the liquid interface influence on the low-cost piezoelectric transducer response by means of the PLB method for EEM monitoring. The results obtained shows that there is great influence on the signal obtained when the piezoelectric transducer is in contact with the liquid interface. The results also shows that the influence is more preeminent on certain frequency values.